Method

1. For the brine, place salt and water in a pot on high heat and stir until the salt is dissolved. Remove from heat and allow to cool completely. Using a sharp serrated knife or kitchen scissors, cut the chicken through the back bone and press it down flat in a deep baking dish, skin side down. Pour over the cold brine until the chicken is mostly covered, cover with cling film and refrigerate overnight.
2. Pre-heat the oven to 160C.
3. For the marinade, mix olive oil, white wine vinegar, garlic, paprika, pepper and cumin until combined. Remove the chicken from the brine, rinse under cold water and pat dry. Discard brine. Gently pair the skin away from the breasts and place 1/3 of the marinade under the skin. Place chicken skin side up in a baking dish and coat the skin with remaining marinade. Cover loosely with foil and roast in a low oven (170C) for 30 minutes, then remove foil and turn up the heat to 230C and roast for a further 15 minutes, or until the skin is golden and crunchy.
4. To start the sauce, we first make passionfruit juice. Halve the 4 passion fruit and scoop out the seeds and flesh into measuring jug, then add just enough water to make 150ml. Pour into a blender and using a quick pulse, mix for a few seconds, being careful not to over blend as the seeds will be hard to extract. Pass through a fine plastic sieve (metal can sometimes react with the acidity of the passionfruit) using the back of a spoon to push the juice through. Discard seeds and reserve juice.
5. To complete the sauce, place capsicums and chillies on a lined baking tray and into the 230°c oven to blacken. Alternatively you can blacken the skins over a gas flame. Remove and place in a bowl and wrap tightly with cling film to steam. Once steamed peel off the skin and discard along with the seeds. Place the capsicum and chilli flesh in a blender, along with passionfruit juice and olive oil. Puree until smooth and season with salt and pepper. Remove from the blender and stir in very finely chopped coriander roots and stems, and season. Place the sauce in a serving bowl and top with the flesh and seeds of the 1 extra passionfruit.
6. To serve, sprinkle coriander leaves over the roast chicken and serve the sauce alongside.